Heat-developable photographic light-sensitive material and methods for forming images using such materials are well known and are described in detail, for example, in Shashin Kogaku no Kiso (Fundamentals of Photographic Engineering), Corona Co., Ltd., pp. 553 to 555 (1979), Eizo Joho (Image Information) (April 1978), p. 40, and Neblette's Handbook of Photography and Reprography, 7th Ed., Van Nostrand Reinhold Company, pp. 32 to 33 (1977), U.S. Pat. Nos. 3,152,904, 3,301,678, 3,392,020 and 3,457,075, British Pat. Nos. 1,131,108 and 1,167,777, and Research Disclosure, RD No. 17029, pp. 9 to 15 (June 1978), etc.
Typical examples of organic silver compounds which can be used in heat-developable light-sensitive materials include silver salts of aliphatic carboxylic acids and silver salts of aromatic carboxylic acids.
Further examples include silver salts of aliphatic carboxylic acids having a thioether group, as described in U.S. Pat. No. 3,330,663.
However, these silver salts of carboxylic acids are disadvantageous in that they release acids after reacting with reducing agents to reduce the pH in the layer, and thus subsequent development is restrained.
Organic silver salts other than silver salts of carboxylic acids include silver salts of compounds having a mercapto group, or a thione group, and derivatives thereof.
Additional examples include silver salts of compounds having an imino group such as silver salts of benzotriazole or derivatives thereof, etc., as described in Japanese Patent Publication Nos. 30270/69 and 18416/70.
However, these silver salts are disadvantageous in that they release a compound which restrains development, or, in some cases, causes fog after reacting with reducing agents. Furthermore, they sometimes inhibit the functions of spectral sensitizing dyes, and high sensitivity cannot be obtained.
Moreover, in view of shortening processing time, a method wherein a step for forming imagewise mobile dyes by heating and a step for transferring the mobile dyes to a dye fixing layer are carried out at the same time has been as described, for example, in Japanese Patent Application (OPI) No. 218443/84, etc. (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"). However, it has been desired to provide a more rapid process.